64 THE ORGANIZATION OF 



as to form a notch, and curls upon itself in a spiral form. The 

 space (s) which is bounded by the rim (c) is called the disc. 

 Close to the notch, and within the little, spiral just spoken of, 

 there is an opening (fig. 30 m, and fig. 31 m) which leads down- 

 wards into an elongated funnel-shaped channel (fig. 31 m l ) ; the 

 first is the mouth and the second is the throat or oesophagus. 

 The latter tapers to a point (m 2 ) after plunging for a short dis- 

 tance obliquely across and backwards into the centre of the body ; 

 and its further extent can only be detected when the food passes 

 through it, on its way to the general digestive cavity. 



Usually at about one third of the way around to the opposite 

 side of the trumpet, but sometimes nearly half round, as in this 

 figure, by some peculiarity in the mode of expansion, there is a 

 globular cavity (cv) from which a tube (cv 1 ) extends, with a gen- 

 tle taper (cv 1 ) to the extreme opposite end (a) of the body. By 

 the rhythmical contraction and expansion of the cavity and the 

 tube, you will recognize them to be the components of a con- 

 tractile vesicle. The contraction of this heart-like body occurs 

 once in three quarters of a minute, when the fluid in the globular 

 portion (cv) is forced backward into the narrow channel, (cv 1 , cv 2 ,) 

 which, in its turn, after expanding very sensibly, and receiving 

 the fluid, contracts, and returns it to the original starting-point. 

 Looking upon that side of the trumpet at which the mouth is 

 placed as the lower or abdominal side of the body, the contrac- 

 tile vesicle may be said to be normally situated at or about the 

 left side. 



The digestive and the circulatory systems are the only parts 

 of the organization essential to life that are known to investiga- 

 tors; but recently I have been led to believe that I have dis- 

 covered the nervous system, or at least a part of it, and that too 

 in the very region of the body where there is the most activity, 

 and therefore more likely than elsewhere to have this system 

 most strongly developed. Immediately within the edge of the 



The two resultants are just on the point of separating at a 1 ; s, the protruded 

 convex outline of the disc ; m 1 , the throat in the distance ; cv, the contractile 

 vesicle next the eye ; n, the reproductive organ. Original. 



